1. Field of the Invention
The present invention relates to a method and system for image mapping for generating composite images by mapping images. More specifically, the invention relates to a method for simulating high-quality images for color or monochromatic gray scale images or for calculating the position information of grid points found on images or photographs and a method and system for texture mapping.
2. Description of the Prior Art
There are two types of prior arts of the present invention; that is, particularly one relates to the aforementioned image simulation and the other relates to texture mapping. Firstly, the prior art of image simulation will be described.
An image simulation art for reading an image in a computer as data and for changing colors and patterns in a specific area using the image processing art so as to produce an image indicating a quite different scene is required in the design and presentation fields at present.
In this case, as mentioned in Japanese Patent Laid-Open No. 63-293676 (hereinafter referred to as Prior Art 1), by separating an inputted color image into an intensity component and a color component, processing at least the color component among them, and composing and outputting it with the intensity component, a simulation reflecting the shadow and shade originally existing in the object body in an image can be performed.
Furthermore, as mentioned in Japanese Patent Laid-Open No. 63-237172 (hereinafter referred to as Prior Art 2) or Japanese Patent Laid-Open No. 3-41570 (hereinafter referred to as Prior Art 3), by extracting object body color vectors and light source color vectors in a specific area of an inputted color image from the pixel color vectors in the above area, by expressing the color vectors of all the pixels in the above area in a vector linear combination of the object body color vectors and light source color vectors, and by changing the object body color vectors and light source color vectors so as to reconstruct the color vectors, a high-quality simulation including the shadow and shade and the reflected section can be performed.
The following problems are imposed by the above prior art.
(1) When a full color image is separated into an intensity component and a color component and the color component is changed and then recomposed with the intensity component, the texture which originally exists in the initial image is passed to the intensity component and reflected to the final composite image. This method is effectual in an application with the intention of additionally reflecting the initial texture to the composite image, though it cannot satisfy the needs to change the fine texture of the initial image to a different texture and to reflect only the information of shadow and shade of the initial image to the result. The information of shadow and shade mentioned above indicates a distribution of brilliance which is generated on the surface of an object body by a shadow generated because a light beam irradiated onto the object body is blocked off or weakened or by a shade caused by changes in the received light intensity depending on the angle between the light beam and the surface of the object body or a distribution of brilliance caused by a multiformal distribution of light intensity generated because an originally sharp light beam is spread by refraction of the light beam which passes through some other objects and by scattering of the light beam which strikes some other objects. PA1 (2) When the reflection of the information of shadow and shade is limited to a reference to the intensity component, the following problems are caused. PA1 (3) Application of the simulation method that a full color image is separated into an intensity component and the color component is changed and then recomposed with the intensity component to a gray scale image cannot be realized because the gray scale image is the intensity component itself, so that information other than the intensity component cannot be extracted. PA1 (4) By a method for simulating an image by extracting object body color vectors and light source color vectors in a specific area of an inputted color image from the pixel color vectors in the above area, by expressing the color vectors of all the pixels in the above area in a vector linear combination of the object body color vectors and light source color vectors, and by changing the object body color vectors and light source color vectors so as to reconstruct the color vectors, a simulation for changing the texture to a texture which is not monochromatic cannot be performed because the unique object body color vector is given to the object area. PA1 (5) Unless the condition that the object area has a unique object body color is satisfied, vectors cannot be extracted. Therefore, an area including a texture which is not monochromatic cannot be simulated.
(2-1) There is a possibility that the information of object body colors which is independent of the information of shadow and shade is also included in the information of shadow and shade at the time of simulation and the information of shadow and shade cannot be reproduced precisely. PA2 (2-2) Since the information of light source colors cannot be obtained, differences in the shadow and shade caused by a different color light source cannot be reproduced precisely.
Next, the prior art of texture mapping will be described. To extract the position information of an arbitrary point on an image, a point which moves depending on the input information is superimposed on the image and the position information of the extracting point is extracted from the input information of the movable point when the movable point is overlaid with the extracting point. To extract the coordinate value of an arbitrary point on a digital image of a computer, the object image is generally displayed on the display unit, and the mouse cursor is superimposed on it, and the mouse cursor is moved by moving the mouse, and the input coordinate value of the mouse when the mouse coincides with the extracting point is taken as a coordinate value of the point. Hereinafter, extraction of a coordinate value on the above principle is called "direct extraction by mouse". However, a trackball, light pen, touch panel, or digitizer is used as an input unit of a computer other than a mouse and the same operation can be performed by any of them. Therefore, this operation is not restricted only to a mouse.
In F. Ito and others, "Texture Simulation System in Consideration of Simplicity and Reality", 39th (latter half of the first year of Heisei) National Convention of Information Processing Society of Japan (hereinafter referred to as Prior Art 4), a method is described that in the texture mapping for composing a texture image, in order to compose a texture image so that it matches the composition of a projection of a perspectively projected three-dimensional space, the coordinate values of the vertexes of the corresponding tetragons on the two images of the texture image and the projection are directly extracted by the mouse or another means, and the parameters for projection transformation between the two images are calculated from those coordinate values, and the texture image is transformed and composed by this projection transformation.
Furthermore, in the above Prior Art 4, a method is described that in the texture mapping for composing the first image with the second image, the contour of the area wherein the texture mapping is performed on the first image is determined by the direct extraction by the mouse or another means so as to restrict the range for texture mapping.
The following problems are imposed by the above prior art. A problem (Problem 1) in a method that necessary points are all extracted directly by the mouse or another means so as to extract the position information of an arbitrary point on an image will be described hereunder. For example, even when there is a regularity among the position information contents of some extracting points, this method requires the same procedure to be performed repeatedly at all the necessary points and the operator's job becomes enormous when there are a large number of points. Furthermore, since an independent procedure is used to extract each position information in this case, the original regularity of position information is ignored.
Another problem (Problem 2) in a method that in the texture mapping for composing a texture image for a projection of a perspectively projected three-dimensional space, the coordinate values of the vertexes of the corresponding tetragons on the two images of the texture image and the projection are directly extracted by the mouse or another means, and the parameters for projection transformation between the two images are calculated from those coordinate values, and the texture image is transformed and composed by this projection transformation will be described hereunder. For example, even when there is a regularity among the coordinate values of a plurality of extracting points when the same texture image is mapped one after another in a plurality of areas on the projection on the same plane in the three-dimensional space, this method requires the same procedure to be performed repeatedly at all the necessary points and the operator's job becomes enormous when there are a large number of points.
Furthermore, since an independent procedure is used to extract each coordinate value in this case, the original regularity of coordinate values is ignored. A further problem (Problem 3) in a method that in the texture mapping for composing the first image with the second image, the contour of the area wherein the texture mapping is performed on the first image is determined by the direct extraction by the mouse or another means so as to restrict the range for texture mapping will be described hereunder. Since the range for the second image is not restricted in this method, it is necessary to prepare an image wherein every pixel can be subjected to texture mapping. Furthermore, in a method that the contour of the area is specified when the range of first image texture mapping is restricted, when setting whether or not to perform texture mapping arbitrarily for each pixel on the first image, the specification of the area is very complicated and the operator's job becomes enormous.